Until recently, the tendency has been to think of this rather than to speak of it—or to speak of it very delicately, lest the hard-won ideal of diversity be imperiled.

But nobody with any feeling for the zeitgeist can avoid noticing the symptoms of white unease and the additionally uneasy forms that its expression is beginning to take.

Concerns of this kind are not confined to the Tea Party belt. Late professors Arthur Schlesinger and Samuel Huntington both published books expressing misgivings about, respectively, multiculturalism and rapid demographic change.

But these were phrased so carefully as almost to avoid starting the argument they flirted with.

More recently, almost every European country has seen the emergence of populist parties that call upon nativism and give vent to the idea that the majority population now feels itself unwelcome in its own country. The ugliness of Islamic fundamentalism in particular has given energy and direction to such movements.

It will be astonishing if the United States is not faced, in the very near future, with a similar phenomenon. Quite a lot will depend on what kind of politicians emerge to put themselves at the head of it.

Saturday’s rally was quite largely confined to expressions of pathos and insecurity, voiced in a sickly and pious tone. The emotions that underlay it, however, may not be uttered that way indefinitely.